( "éxxxv =) 
to its thickness, but its surfaces must practically be simple 
planes. A piece of corrugated iron could not act as a saw, 
however one of its edges might be denticulated. A sort of 
“sawing ” may, no doubt, be done with a file or a rasp, but it 
can hardly be considered as ideal carpentry. 
Now, if we look at almost any Sawfly’s implement in any 
aspect but the lateral, we shall notice that it is utterly unlike 
any conceivable blade of a true saw. It is generally of very 
unequal thickness, and particularly thick in parts of it which, 
we know as a fact, do enter into the incisions made by it. 
Sometimes it is not blade-like at all, but more resembles a 
spear-head, or some horrible barbed instrument of torture or 
savage warfare—admirably adapted to mangle substances but 
certainly not to ‘‘saw” them. Some even of those which at 
first sight are comparatively possible saws (about as much so 
as a rasp) prove on closer examination to have their sides 
corrugated and armed with erect processes, to an extent which 
would make it impossible for them to pass evenly through any 
substance less soft than butter. Again, even in the lateral 
view of some so-called saws (Cladius, Lophyrus, ete.), it is 
seen at once that the serrations do not form a continuous 
line of ‘‘teeth” along the lower margin, but run in parallel 
rows across the blade (transversely). The notion of a saw 
embellished by additions which add to its powers those of 
certain other tools, is at first attractive and seems conceivable. 
But when any one has really thought out the necessary action 
of an instrument shaped like many of these so-called saws on 
such materials as they are known to be employed upon, and 
has seen the movements made by them when actually so 
employed by the living insects, he will inevitably come to the 
conclusion that though the process does include a kind of 
“sawing,” or perhaps rather ‘‘carving,” this is neither its 
sole nor even its chief ingredient. The real essence of the 
operation is first to pierce, then to mangle and lacerate, and 
also to carve (but hardly to saw in the strictest sense) wntil 
a pin-prick has become enlarged into a pocket. There is no 
“saw-dust,” no ‘ groove” formed by clearing away and abolish- 
ing some part of the material operated on. Even the tooth- 
like undulations of the inferior margin, which have obtained 
